A nano-nickel electrochemical sensor for sensitive determination of chemical oxygen demand

Abstract

Nano-nickel particles (nano-Ni) were electrodeposited on the surface of a glassy carbon (GC) electrode under −0.9 V for 25 min, and then used to construct an electrochemical sensor for sensitive determination of chemical oxygen demand (COD). The parameters such as electrolyte, deposition potential, deposition time and surface morphology were investigated. It was shown that nano-Ni film with high electrocatalytic activity was stably modified on the surface of the GC electrode, which could be used to effectively oxidize a wide spectrum of organic compounds. Under optimized conditions, the linear range was 10–1533 mg L⁻¹ and the detection limit was as low as 1.1 mg L⁻¹. Subsequently, this sensor was used to detect the COD values of different water samples and the results were linearly correlated to those by the classic dichromate method (R = 0.9493, p < 0.01, n = 54). This confirmed the reliability and practicality of the proposed method in the determination of COD in various water samples.